The points is that ALL the best Kenyans in 5000 / 10000 / HM and Marathon, and steeple (I mean the top 10-15) ALWAYS run at a absolutely normal level of EPO, and this level NEVER changes during every type of test, in competition or out of competition. This is the reason because all the top kenyan runners hope that the biological passport can work more consistently in the future : because they don't have anything to fear, while in many other Countries a lot of athletes start to be not very tranquil...
You must understand that with top athletes we use periodic blood test (who doesn't use cant be a good coach) in order to see the level of ferritine, of iron and transferrina, that after some kind of workouts (for example when we use lactic training) normally decrease. We need to know this data because, when we see low level of ferritine, we know that the athlete needs a new period of aerobic training, reducing the intensity. Ferritine can be considered the iron the athletes have in their store : if the level is low, they need to wait to recover the normal level before training very hard. This is the reason, for example, because all the runners going in altitude from sea level need to take folic acid together with vitamin B and C, in order to increase the ability in absorbtion of Oxygen because of the lack of this gas in the air.
This, obviously, is not something regarding Kenyans and Ethiopians : for them the situation is normal, and they don't need to change their behavior.
Another thing I already explained a lot of times, but it seems many don't understand :
a) when you go to altitude from sea level, the new situation provokes a reaction at the level of medulla with the result to increase the number of erythrocytes (not always, but in 80/85% of cases). So, after a short period of time, these athletes see their hematocrit going up (from 3 to 5 points) because of the higher number of RBC.
b) when you STAY in altitude, you don't have any new stimulus, but you have ADAPTATION. This means that the number of RBC remain constant (and not very high, African have less RBC than people of sea level), but thei globular volume is bigger. And all the top African runners have a normal level of hematocrit (rarely over 45), the most part of cases lower than the level of European and American runners.
c) at the end, they have less viscosity than athletes staying at sea level. We can see this practically in a very simple way : if we have an athlete able to reach a max heart pulse of 200 beats / min at sea level, and we ask him to go at maximal speed for 300m climbing (that is a good way for reaching the max possible heart beats) at sea level, he really reach 200. We ask him to do the same in altitude, and he's not able to overtake 180 (about 10% less). If we ask to a top Kenyan / Ethiopian to do the same in altitude, he reach 200 or more. If he repeats the same at sea level, nothing changes. This is possible because the blood fluidity is very much higher than in athletes living and training at sea level.
But, of course, everybody can know from books and experiments done at sea level with different type of animals.... and supposes to be the owner of the truth.
At the end, we continue to produce clean results with top athletes, and who believes in doping continue to lose....
good situation for coaches believing in training and knowing where it's possible to arrive without shortcuts.